“Today, we’re thrilled to share that WhatsApp has more than 700 million monthly active users. Additionally, every day our users now send over 30 billion messages,” wrote Koum.

“As humbled and excited as we are by these numbers and our continued growth, we’re even more excited to keep building a great product in 2015.”

WhatsApp’s rapid growth has thus continued since its acquisition by Facebook, which announced the then-$19bn deal in February 2014, before completing it at the higher price in October due to the inclusion of Facebook shares that had risen in value in the intervening months.

WhatsApp’s last public milestone was 600 million active users in August 2014, so it has added new users at a rate of around 25 million a month since then. Previously, the app grew from 200 million active users in April 2013 to 400 million by December that year.

WhatsApp’s co-founder has been steadfast in his promises to users that being owned by Facebook would not change its principles on advertising – it doesn’t carry them – and privacy.

“Respect for your privacy is coded into our DNA, and we built WhatsApp around the goal of knowing as little about you as possible,” wrote Koum in March 2014, in response to media speculation about how the acquisition might change WhatsApp.

“If partnering with Facebook meant that we had to change our values, we wouldn’t have done it. Instead, we are forming a partnership that would allow us to continue operating independently and autonomously.”